Characterization Of A Multiple-Step In-Situ Plasma Enhanced Chemical Vapor Deposition (PECVD) Tetraethylorthosilicate (TEOS) Planarization Scheme For Submicron Manufacturing

This paper presents a manufacturable process to deposit dielectric films capable of void-free filling of submicron spaces between adjacent interconnect lines as well as local planarization of topography using conformal TEOS-based oxides and in-situ etch processes. The deposition planarization process is user programmable and is accomplished entirely in a single multi-chamber system (Applied Materials Precision 5000) in one cassette-to-cassette operation. Data on the step coverage and topographic gap filling characteristics of the TEOS oxide deposition and etchback sequences are presented. Analyses of material properties and the electrical stability of the TEOS-based oxide films deposited in this system indicate that the films are suitable for interlevel dielectric applications in submicron devices. Film properties such as stress, thermal shrinkage, density, moisture absorption, and dopant incorporation were characterized for the two types of low temperature TEOS-based oxides used in the process, and these are compared to the properties of low temperature SiH4-based LPCVD oxides. The results show that the TEOS films compare favorably to the "industry standard" SiH4-based films. SIMS analysis was used to investigate the purity of the TEOS oxides. The signals of aluminum, iron, and other trace metals were at or below their detection limits, for both the PE-TEOS and the thermal ozone-TEOS oxides. The carbon content of the PE-TEOS film was 0.8 atomic percent while both the thermal ozone-TEOS and the LPCVD SiH4 oxides had less than 0.2 atomic percent. Electrical stability of the composite TEOS oxides was evaluated using bias-temperature stress C-V analysis. Undoped and phosphorus-doped PE-TEOS oxides produced lower Hatband voltage changes than the reference LPCVD SiH4 oxides. The undoped PE-TEOS films were found to have mobile ion charge densities of 7.7*109 cm-2, compared with the LPCVD SiH4 oxide values of 1.2*1011 cm -2. Device level electrical testing of devices built using the TEOS oxides showed no electrical anomalies such as gate charging and the devices have successfully undergone reliability and lifetime testing.